Tufting machine



' Dec. 3, 1963 R. E. H. HAMILTON ETAL ,7

TUFTING MACHINE Filed 0st. 24., 1960 2 Sheets-Sheet 1 //7 yen/01 46 RE Hamsflam/fan d 42 C//ff0rdA/0/ne Brycmf By their afforneys Defl 1953 R. E. H. HAMILTON ETAL 3,112,717

TUFTING MACHINE Filed Oct. 24, 1960 2 Sheets-Sheet 2 7b Power Supply /n l/fl/O/S A. [Harris Ham/#00 C/ifordll/d/he Bryan/ 5y fhe/kalfomeys United States Patent 3,112,717 TUFlflN'G MACHINE R. E. Harris Hamilton (Ilifiord Airline Bryant, Dalton, Ga, assignors to abin ilrafts, lno, Dalton, Ga, a corporation of Georgia Filed (feet. 24, 19 4), Ser. No. 64,413 19 Claims. (@l. 112-7?) This invention relates to a tufting machine for making rugs, carpets and other tufted fabrics. More particularly, it relates to a tufu'ng machine for making high and low pile tufting by the penetration of a bank of yarn-carrying nee les through a backing sheet or cloth, to form a row of yarn loops in the sheet, and shortening selected loops efore forming a succeeding row of loops.

The invention is distinguished from certain prior processes and machines which shorten selected loops by pulling back yarn from them during the formation of a succeeding row of loops. According to this invention, the change in pattern from high to low tufting and vice versa is made in the current loop and not one row later.

An object of the invention is to provide an improved machine or mechanism for maicing high and low pile in selected places in tufted fabrics according to a pattern.

Anot er object is to provide an improved tufting machine of the aforesaid type which will make the currently-formed loop of the desired height without regard to the height of, or the necessity of, making a succeeding loop.

Another object of the invention is to provide an improvement in tufting machines to accomplish the aforesaid objectives and functions which can readily be adapted to known or existing machines.

Other objects and advantages of the invention will appear as the invention is described in connection with the accompanying drawings.

in the drawings:

FIG. 1 is a diagrammatic View in side elevation of a tufting machine mechanism in which the invention is incorporated.

FIG. 2 is a View similar to PEG. 1 with the parts in another position.

FIG. 3 is a view similar to FIG. 1 of a slightly modifled form of the machine illustrated in FIGS. 1 and 2.

PEG. 4 is a view Slr iilar to FEGS. 1-3 of another form of the invention.

FIG. 5 is a fragmentary perspective view of a movable yarn guide employed in the invention.

FlG. 6 is a fragmentary side elevation View, partly in sec :1, of the movable yarn guide of F3. 5.

7 is a fragmentary view in side elevation of the cam-ope. g arrangement for the loop-shortening bar used in the invention.

FIG. 8 is a fragmentary side elevation view of another form of cam-operating mechanism for the loop-shortening b r to give more rapid movement.

PEG. 9 is a fragmentary detail View (enlarged with respect to FIGS. 1 and 2) of the yarn guide of FIGS. 1, 2 and 3.

PEG. 10 is a side elevation view, partly in section, of the whole yarn fee ing and loop-height-control apparatus.

Referring to drawings, a bank of needles N is mounted in a needle bar or head it? carried by a plurality of spaced thrust bars 12 suitably guided for vertical movement in the guide members (not shown) in the machine frame and conventionally reciprocated vertically by the usual operating mechanism (not shown).

The needles penetrate a cloth or backing sheet C which is fed and pass over a table or work-supporting bar or plate S as the needle bar is reciprocated. Conventional loopers L (one for each needle) are rockably mounted below the table or work-support on a horizontal rock shaft 14 in position to be rocked by conventional means (not shown) in timed relation to the needle reciprocations so as to catch the loops formed by the needles as they penetrate the cloth and to hold the loops as the needles rise and withdraw from the cloth.

The parts and functions as thus far described are conventional and known and, hence, no further description or illustration of them is needed by those skilled in the art.

The timing of the engagement or entrance of the loopers within the yarn loop is such that the looper is out of the loop at the top dead-center of the needle reciprocation. During the descent of the needles, the looper starts to pivot toward the path of its needle. its point does not reach the line or" travel of the needle until the eye of the needle has passed the arc of travel of the looper bill because the loop must be present in order to be entered by the looper bill as the looper point moves across the line of travel of the needle.

The looper point has entered the loop before the needle starts to ascend and the looper withdraws during the ascent of the needle. Its bill is completely withdrawn just before the needle reaches the top dead-center position.

The yarn Y is fed to the needles from a variable feed mechanism as described in Hackney et al. Patent No. 2,954,865, issued October 4, 1960. By this feed means, a fast or slow feed of yarn by reason of a yarn guide roll such as 122 and 1.24 or 132 and 134 engaging either a faster or slower rotating feed roll, such as fast roll 114 or slow rolls 112, 116 provides enough yarn for a high loop (fast feed) or only enough for a low loop (slow feed). The feed is individual for each of a plurality of units, each of which may comprise one needle and yarn end or several needles and yarn ends. The feed is also according to a pattern which is laid out on a rotating drum such as 139. By means of electrically actuated means, electric solenoid operated valves res, 7t? and pneumatic cylinders 144, 54 individually control the individual units.

The yarn from the variable feeding means passes between a pair of parallel loosely intermeshing fluted or toothed rolls 2% and 22 mounted on horizontal shafts and located between the feeding means and the needle bank, and preferably above the needle bank.

These rolls may be mounted on the machine frame in any suitable fashion and driven by the machine opera ing mechanism through appropriate gearing. They are not tightly mtermeshed and will allow some slippage of the yarn. However, they act sufficiently on the yarn to serve as auxiliary feed rolls and add to the resistance of the yarn supply so that any pulling on the yarn by the hereinafter described loop-shortening bar 4 0 will pull yarn from the just-fonned stitch rather than from the feed.

From the fluted rolls 2t and 22, the yarn goes downwardly to a horizontal yarn-guide bar 16 extending across the machine and fixedly mounted in any suitable fashion on the machine frame. There is a hole 15 in the yarn guide bar for each yarn end.

'From the guide bar 16, the yarn goes in a generally horizontal direction to a similar, fixed yarn-guide bar 17 also suitably mounted horizontally on the machine frame; and from thence the yarn goes downwardly through still another fixedly mounted horizontal yarn-guide bar 13 from which the yarn goes directly to the needles N.

In order to provide for the making of a long or a short loop, means are provided to pull back yarn from the currently-formed loop after such loop has been inserted in the cloth, but before the needle starts upon the formation of another loop. For this purpose, a fiat narrow movable yarn-guide member '36 with at least one hole 31 therein for the yarn is mounted for the vertical movement on the end of a piston rod 32 extending from the bottom of a cylinder 34 in which moves a piston 36 fixed to the upper end of the piston rod 32. A coiled compression spring 33 within the cylinder 34 presses at its lower end against the bottom of the cylinder and at its upper end against the underside of the piston 36, thus biasing the piston rod vertically upward into the position shown in FIG. 2.

Air is admitted to or exhausted from the cylinder 34 through an air connection or pipe 37. The admission of air to lower the piston and yarnguide bar 33' is controlled by the energization of an electrical solenoid valve 39 in the compressed air line. The operation of this valve '39 is under control of the same electrical actuating means, namely a pattern on the rotating drum 1% (as described in Patent 2,954,865 above mentioned) as controls the fast and slow yarn feed.

When the movable yarn-guide 36 is in the position of FIG. 1, that is to say when the piston and yarn-guide are depressed due to the pressure of air within the cylinder 34 and yarn is fed for the formation of the long loop, a long loop will be formed as the needle end reciprocates.

In order to form a short loop, a 1oop-shortening bar 40 is mounted upon a fixedly located horizontal shaft 42 suitably pivotally mounted in the machine frame. The loop-shortening bar 49 preferably is of substantially L-shape, as viewed in side elevation and is pivoted at the end of its longer leg. It is of such length that its shorter leg will move in an are substantially midway between the fixed yarn-guide 17 and the movable yarnguide 30.

In order to rock the loop-shortening bar 4-9, a cam plate 44 is fixedly mounted upon an extending end of the horizontal shaft '42 of the loop-shortener 40. This cam plate 44 has a cam slot 45 in the form of an oblique angle formed therein, in which travels a cam follower pin 45 extending perpendicularly to the plate 44 and perpendicularly from a rotating carrier plate 47. This carrier plate is mounted upon the end of a horizontal shaft 4 8 which is driven in any suitable fashion from the main drive of the mechanism of the machine in timed relation to the needle and looper actions.

As viewed in FIG. 7, the plate l7 rotates counterclockwise carrying the cam follower 46 in a counterclockwise orbit. This causes the cam plate 44 and shaft 42 and loop-shortener 45 to rock, moving the loopshortene-r 40 between the full-line and the dotted-line positions of FIGS. '1 and 2.

When the bar 40 is down in the dotted position of FIG. 2, the length of yarn between the movable guide '31 and fixed guide 17 will be deflected, pulling back yarn through the fixed guide 18 and needle N from the just-formed loop, thus shortening it.

When the movable yarn guide 39 is down in the position of FIG. 1 and the loo -shortener 4 moves down to the dotted position of FIG. 1, the just-formed loop will not be shortened. However, as will be observed in the figure, there will be a very slight deflection of the yarn (as shown in dotted lines) for the purpose of evening up the long loops as they are formed. This evening up makes the overall tufting in the long loops more even than would otherwise be the case.

In the event that the evening is not desired, the form of the invention illustrated in FIG. 3 will be employed 'wherein the movable yarn guide 30 is longer or moves down further than in FIG. 1 with the result that the bar 40 in its lowered or dotted position does not deflect at all the portion of the yarn which lies between the movable yarn-guide 3t} and fixed yarn-guide 17. The long loop currently formed, therefore, will retain its original length.

In FIG. 4, another form of the invention is illustrated which difiers from the form of FIGS. 1-3 in the respect that the fixed yarn-guide i7 is omitted. Instead, the

'4 movable yarn guide in this form is of substan'dally J shape having at its lower end a transverse portion 31' and an arm 33' parallel to the main portion 39' of the yarn-guide.

In the short arm 33', there is an aperture 3311 provided for the yarn and a similar aperture 3971 is provided in the main portion 59'. same as that illustrated in the further form of FIGS. 5 and 6 hereinafter described, except that in the present or FIG. 4 form, there is only one hole in each leg of the J. In this form of the invention when the air pressure is not exerted and the piston rod and guide are up (as illustrated in full lines in FiG. 4), the yarn will be pulled back when the loop shortener 4t descends to the dotted-line position. When air pressure enters the cylinider 3 i and the yarn guide is depressed, the yarn will be outside the path of movement of the loop-shortener 4i) and will not be affected by the descending movement of the same.

An advantage of the J-shaped yarn guide is a more 7 positive positioning and holding of the yarn in the path of the loop-shortener 44 which in turn, provides more uniform loop shortening and more even pile. Also a shorter stroke of the loop-shortener is possible for the same pile height.

In narrow gauge machines or Where a thick yarn is used and it is desired to have two yarn ends controlled by one movable J-shaped yarn-guide, the holes through which the yarns pass in the lower end of the movable yarn-guide may be offset as shown in FIGS. 5 and 6'. Thus, one yarn Y may pass through a hole in the main portion 3'5 of the yarn-guide, which hole is lower than another hole in the arm 33 Thus, the portion between the short arm 33 and the main portion Sil of the yarnguide will be inclined upwardly with respect to transverse portion 31 as illustrated in FIG. 5.

On the other hand, the second yarn Y may pass through :a hole in the main portion 3%? of the yarn-guide higher than the hole through which the yarn Y passed. The yarn Y will then pass out through another hole at a lower level in the arm 33 and, thence, will be inclined downwardly with respect to the transverse portion 31 Thus, by staggering the holes in alternation, it is possible to have two yarn ends pass through a narrower yarnguide than would otherwise be possible. Due to the inclination of the portions of the yarns between the arm 33 and the main portion 3% of the yarn-guide, they will be at approximately the same level midway. Hence, when the loop-shortener 40 engages both yarns, it will have the same effect on each and will cause the same amount of pull-back movement on both strands of yar providing evenness of the low pile loops.

It is desirable for the loop-shortener so to act quickly during the ascent of the needles and to complete its pulling back of the yam for the loop being currently formed before the next downstroke of the needle. This can be accomplished by proper shaping of the operating surface of the the cam, providing a peak for a quick downstroke of the loop-shortener 4t} and quick return of the same.

Such a cam is illustrated in FIG. 8 wherein the follower pin 46' is on the end of a cam-actuated lever 44 affixed on the shaft 42. The arm 41' of the loopshortener 45) is very quickly moved counterclockwise in PEG. 8 by the rocking of the shaft 42 as the arm 44 is rocked counterclockwise by the sudden elevation of the: cam follower pin 46' by the peak 47 in the cam track 49. It is equally quickly returned as the peak passes- This enables the loop-shortener to do its Work during the upstroke of the needle bar which is before the next loop is formed. This ensures formation of the current loop of the predetermined and desired height regardless of the height of the preceding or succeeding loop.

In all forms of the invention after loop shortener 40 has acted to develop a shout loop, there will be some The J-shaped yarn guide is the.

excess of yarn, e.g. the amount deflected between the guides 3i '--3-3' which was taken from the currentlyformed loop. If another short loop is to he formed, there will be only enough yarn fed from the main feed mechanism of Patent 2,954,865 through the auxiliary fluted rolls 2i 22 to equal the amount to be contained in the short loop. The needle in its descent will take that amount and also the excess remaining from the previous action of the yarn shortener it because the needle always travels the same distance (and, thence, always requires the same amount of yarnequal to a long loop). After the needle withdraws, the yarn shortener will act again to pull back the same excess. Therefore, only temporary use is made of the excess amount. This will continue as long as short loops are to be developed.

When a long loop is to be developed after a short loop, the feed coming through the auxiliary rolls from the main or variable feed mechanism will be an amount equal to that contained in a long loop; and the yarn guide will be down, i.e. in position (dotted in FIG. 4) to make the action of the shortener 4i; ineffective.

The excess from the previous loop shortening will be present, but will not be needed and will remain until the next short loop is to be developed. Hence, it will be available vhen the above-described needle-penetrating and loop-shortening actions are resumed and will avoid the need for any back drawing from a previously formed loop.

Also in all forms of the invention, the fluted rolls 2%, 22 (which are driven from the main shaft by conventional gearing, not illustrated) are rotated at a speed sufficient to feed forwardly or to deliver all the yarn which is fed to them by the main feed mechanism for a long loo-p, i.e. when the fast feed roll is engaged. Consequently, when the feed is slow (when the slow feed roll is engaged) supplying only enough yarn for a low loop, the hated rolls will be moving faster than the yarn is fed to them. Under those circumstances, the loose mesh of the fluted rolls allows slippage upon the yarn.

Many modifications widiin the scope of the invention Will occur to those skilled in art. Therefore, the invention is not limited to the specific form and configuration of parts as illustrated and described.

What is claimed is:

1. In a tufting machine having a work support over which a back-sheet may pass, a reciprocating yarn carrying needle on one side of said support adapted to penetrate the back-sheet and form yarn loops therein, a looper on the opposite side of said support cooperating wish said needle to hold the loop as said needle withdraws from the sheet, variable yarn feeding means selectively feeding yarn sutficient for a long loop or a short loop, pattern-controlled means controlling said feeding means, the mechanism for making the currently-formed loop of the desired height which comprises yarn guide means at least one of which is movable into different positions for development of a long or a short loop, loopshortening means acting on the yarn adjacent the movable yam guide in one position thereof to develop a short loop, and means operable at selected times during running of the machine for moving said yarn guide into said diiferent positions to render said loop-shortening means ineffective for developing a short loop when a long loop is desired.

2. In a tufting machine mechanism as claimed in claim 1, wherein said pattern-controlled means controls the movement of said movable yarn guide.

3. in a tufting machine having a work support over which a back-sheet may pass, a reciprocating yarncarrying needle on one side of said support adapted to penetrate the back-sheet and form yarn loops therein, a looper on the opposite side of said support cooperating with said needle to hold the loop as said needle withraws from the sheet, variable yarn feeding means selectively feeding yarn sufficient for a long loop or a short loop, pattern-controlled means controlling said feeding means, the mechanism for making the currently-formed loop of the desired height which comprises yarn guide means at least one of which is movable into different positions for development of a long or a short loop, loopshortening means acting on the yarn adjacent the movable yarn guide in one position thereof during the ascent of the needle to develop a short loop, and means operable at selected times during running of the machine for movin said yarn guide into said different positions to render said loop-shortening means ineffective for developing a short loop when a long loop is desired.

4. .A tufting machine mechanism as claimed in claim 1 wherein one yarn guide means is fixed, and said yarnshortening means acts on the yarn between said fixed and said movable yarn guides when said movable yarn guide is in one position.

5. A tufting machine mechanism as claimed in claim 4 wherein s movable yarn guide when moved into another p031). n takes the yarn outside the action of said shortening means.

6. A tufting machine mechanism as claimed in claim 4 wherein said movable yarn guide when moved into another position restricts the action of said shortening means to evening the long loops.

7. In a tufting machine having a work support over which a back-sheet may pass, a reciprocating yarncarrying needle on one side of said support adapted to penetrate the back-sheet and form yarn loops therein, a locper on the opposite side or" said support cooperating with said needle to hold the loop as said needle wi dravvs from the sheet, variable yarn feeding means selectively feeding yarn sufiicient for a long loop or a short loop, pattern-controlled means controlling said feeding means, the mechanism for making the currently-formed loop of the desired height which comprises movable yarnguide means defining a predetermined length of yarn and adapted to move both ends of said length into different positions, loop-shortening means acting on said length in one position of the yarn-guide means to develop a short loop, and means operable at selected times during running of the machine for moving said yarn guide into said different positions to render the action of said loopshortening means ineffective to form a short loop when the loop is to remain long.

8. u a tufting machine having a work support over which a back-sheet may pass, a reciprocating yarn-carrying needle on one side of said support adapted to penetrate the back-sheet and form yarn loops therein, a looper on the opposite side of said support cooperating with said needle to hold the loop as said needle withdraws from the sheet, variable yarn feeding means selectively feeding yarn sufiicient for a long loop or a short loop, pattern-controlled means controlling said feeding means, the mechanism for making the currently-formed loop of the desired height which comprises a movable yarn guide carrying a plurality of yarns passing through openings and adapted to move a length of yarn into different positions, an opening for one yarn being offset from an opening for another yarn causing adjacent lengths of said yarns to incline differently, loop-shortening means acting on said lengths in one position of said yard guide to develop equal short loops, and means operable at selected times during running of the machine for moving said yarn guide into said different positions to render the action of said loop-shortening means ineffective for developing a short loop when long loops are desired.

9. In a tufting machine having a work support over which a bac. -she-et may pass, a reciprocating yarn-carrying needle on one side of said support adapted to penetrate the backsheet and form yarn loops therein, a looper on the opposite side of said support cooperating with said needle to hold the loop as said needle withdraws from the sheet, variable yarn feeding means selectively feeding yarn sufficient for a long loop or a short loop, patterncontrolled means controlling said feeding means, the mechanism for making the currently-formed loop of the desired height which comprises a movable yarn guide carrying a plurality of yarns and supporting each yarn at two spaced points, the points of support of adjacent yarns being staggered to increase the number of yarns able to be carried, loop-shortening means acting on the yarns between their points of support in one position of said yarn guide to develop equal short loops, and means operable at selected times during running of the machine for moving said yarn guide into said different positions to render the action of said loop-shortening means ineffective for developing a short loop when long loops are desired.

10. A tufting machine mechanism as claimed in claim 1 having auxiliary feeding means acting on the yarn before it reaches said guide means and preventing pulling of yarn from the supply during said loop shortenin 11. A tufting machine mechanism as claimed in claim 1 having a pair of fluted loosely meshing yarn feed rolls acting on the yarn before it reaches said guide means and preventing pulling of yarn from the supply during said loop shortening.

12. A tufting machine mechanism as claimed in claim 1 having auxiliary feeding means driven at constant speed and acting on the yarn before it reaches said guide means, the action of said feeding means on said yarn being sufiicient to prevent pulling yarn from the supply during shortening but loose enough to allow slippage when the yarn fed in is less than the feed rate of the auxiliary feeding means.

13. A tuiting machine mechanism as claimed in claim 12 wherein the auxiliary feeding means comprises a pair of fluted loosely intermeshing rolls driven at a speed to feed yarn for a long loop.

14. in a tufting macmne having a work support over which a back-sheet may pass, a bank of yarn-carrying needles on one side of said support adapted to penetrate the back-sheet and form yarn loops therein on the opposite side of said support, a looper cooperating with each needle to hold the loop as the needle withdraws from the sheet, variable yarn feeding means selectively feeding yarn to selected needles for a long loop or for a short loop, pattern controlled means controlling said feeding means, the mechanism for making the currentlyforrned loop or" the desired height which comprises yarnguide means at least one of which is movable into different positions for development of a long or a short loop, loop-shortening means acting simultaneously on selected yarns from which short loops are to be developed, and means operable at selected times during running of the machine for moving yarn guides of the unselected yarns to render said loop-shortening means ineffective for developing a short loop when a long loop is desired.

15. A tufting machine mechanism as claimed in claim 14 having the same pattern-controlled means controlling the movement of said movable yarn-guide as controls the yarn feeding means.

16. A tufting machine mechanism as claimed in claim 15 wherein the pattern-controlled means includes an electric solenoid controlling the operation of each movable yarnguide.

17. A tufting machine mechanism as claimed in claim 14 wherein the means to render the shortening means inefifective includes an electric solenoid controlling the operation of each movable yarn-guide.

18. A tut-ting machine mechanism as claimed in claim 14 having auxiliary feeding means driven at constant speed and acting on the yarn before it reaches said guide means, the action of said auxiliary feeding means on said yarn being sufiicient to prevent pulling yarn from the supply during shortening but loose enough to allow slippage when the yarn fed in is less than the feed rate of the auxiliary feeding means. v

19. in a tufiting machine having a work support over which a back-sheet may pass, a bank of yarn-carrying needles on one side of said support adapted to penetrate the back-sheet and form yarn loops therein on the opposite side of said support, a looper cooperating with each needle to hold the loop as the needle withdraws from the sheet, variable yarn feeding means selectively feeding yarn to selected needles for a long loop or for a short loop, pattern controlled means contnolling said feeding means, the mechanism for making the currentlyformed loop of the desired height which comprises yarnguide means defining a predetermined length of yarn and adapted to move both ends of said length into different positions, loopshortening means acting simultaneously on the lengths of selected yarns from which short loops are to he developed, and means operable at selected times during running of the machine for moving yarn guides of the unselected yarns to render said loop-shortening means ineffective for developing a short loop when a long loop is desired.

References Cited in the file of this patent UNITED STATES PATENTS 2,782,741 Smith Feb. 26, 19-57 2,782,905 Smith Feb. 26, 1957 2,842,079 Rice July 8, 1958 2,853,032 Odenweller Sept. 23, 1958 2,853,034 Crawford Sept. 23, 1958 2,876,183 Parlin Mar. 3, 1959 2,878,763 Jackson Mar. 24, 1959 2,932,181 MacCafiray Apr. 12, 1960 2,940,405 Parlin June 14, 1960 2,944,412 Rice July 12, 1960 2,965,054 Masland Dec. 20, 1960 

1. IN A TUFTING MACHINE HAVING A WORK SUPPORT OVER WHICH A BACK-SHEET MAY PASS, A RECIPROCATING YARNCARRYING NEEDLE ON ONE SIDE OF SAID SUPPORT ADAPTED TO PENETRATE THE BACK-SHEET AND FORM YARN LOOPS THEREIN, A LOOPER ON THE OPPOSITE SIDE OF SAID SUPPORT COOPERATING WITH SAID NEEDLE TO HOLD THE LOOP AS SAID NEEDLE WITHDRAWS FROM THE SHEET, VARIABLE YARN FEEDING MEANS SELECTIVELY FEEDING YARN SUFFICIENT FOR A LONG LOOP OR A SHORT LOOP, PATTERN-CONTROLLED MEANS CONTROLLING SAID FEEDING MEANS, THE MECHANISM FOR MAKING THE CURRENTLY-FORMED LOOP OF THE DESIRED HEIGHT WHICH COMPRISES YARN GUIDE MEANS AT LEAST ONE OF WHICH IS MOVABLE INTO DIFFERENT POSITIONS FOR DEVELOPMENT OF A LONG OR A SHORT LOOP, LOOPSHORTENING MEANS ACTING ON THE YARN ADJACENT THE MOVABLE YARN GUIDE IN ONE POSITION THEREOF TO DEVELOP A SHORT LOOP, AND MEANS OPERABLE AT SELECTED TIMES DURING RUNNING OF THE MACHINE FOR MOVING SAID YARN GUIDE INTO SAID DIFFERENT POSITIONS TO RENDER SAID LOOP-SHORTENING MEANS INEFFECTIVE FOR DEVELOPING A SHORT LOOP WHEN A LONG LOOP IS DESIRED. 